Apparatus and method for increased realism of training on exercise machines

ABSTRACT

An exercise machine includes a cyclical actuator and a mechanical energy storage device. Connective structure operatively connects the cyclical actuator to the mechanical energy storage device. Motion of the cyclical actuator urges physical motion of and energy storage in the mechanical energy storage device. The exercise machine further includes an electric machine. A communication pathway enables exchange of data between multiple associated exercise machines such that multiple associated operators on multiple associated exercise machines have a common experience.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/149,869, filed Apr. 20, 2015, PCT Application No. PCT/US2016/028282,filed Apr. 19, 2016, and is a divisional application of U.S.Non-provisional application Ser. No. 15/567826, filed Oct. 19, 2017,titled “Apparatus and Method for Increased Realism of Training onExercise Machines,” the entire disclosures of which are herebyincorporated herein by reference.

TECHNICAL FIELD

In various embodiments, the present disclosure relates generally toexercise machines, and more specifically to exercise machines thatdissipate energy through mechanisms that allow customizable loadprofiles, and to exercise machines having an interconnection capabilitythat enables synchronization of exercise activities.

BACKGROUND ART

Many athletic activities entail the coordination of motions by membersof team. Herein, we term such activities “coordinated sport.” To becompetitive in coordinated sport, team members must build skill,strength, and endurance and learn to coordinate their efforts. Anexample of coordinated effort is, in team rowing, the performance ofoarstrokes of closely similar timing, duration, and power. Anotherexample is, in tandem bicycle riding, the coordination of pedal strokes.Herein, frequent reference will be made to the sport of rowing and toexercise machines pertinent to rowing, but such references areillustrative, not restrictive: other sports, non-sport activities, andtypes of exercise machines are contemplated and within the scope of thedisclosure.

Teams may be trained by field exercise, e.g., actually rowing a boat onwater; however, due to seasonal, weather, and other limitations on fieldexercise, in practice athletes prepare for and supplement field exerciseby working out extensively on trainers, i.e., stationary machines whosemechanics simulate one or more aspects of the sport in question. Atypical trainer comprises one or more mechanisms upon which the user'sbody rests and/or acts (e.g., pedals, oars, seats) and one or moredissipative mechanisms (e.g., air fins, friction pads), typicallyadjustable, which place energetic loads on the user. A typical traineralso comprises an inertial mechanism (e.g., flywheel) that simulates theinertia of one or more athletes in motion along with the inertia of awatercraft, bicycle, or other gear.

Trainers are most often built to accommodate a single athlete.Single-user trainers do not support training of team members in thecoordinative aspects of a given sport, and when only single-usertrainers are available, training in the coordinative aspects of thesport can only occur in field exercises. To overcome this problem, theprior art has developed team trainers, relatively large machines thataccommodate two or more athletes at one time. For example, the rowingsimulator disclosed in U.S. Pat. No. 8,622,876 describes mechanicalganging of single-oar rowing machines for simultaneous training of up to8 rowers. However, in this example, dissipative loads (e.g., ergometers)are driven by each athlete: thus, the performance of one athlete doesnot dynamically affect the loads addressed by other athletes on themulti-user trainer. In another example, the simulated rowing machinedisclosed in U.S. Pat. No. 8,235,874 describes ganging of single-oarrowing machines so as to include mechanical coupling of each rower'sresistance and recovery mechanism to every other's, enabling the crew toalign its power application in a realistic fashion.

Limitations of the prior art for coordinative (i.e., team) traininginclude but are not limited to the following: (1) Athletes working outon isolated machines (e.g., in a single space but not mechanicallyconnected, or in different geographical locations) cannot receivetraining on the coordination aspects of their sport. (2) All athletes tobe trained by a team trainer must assemble at a common place and time touse the team trainer. This entails travel to the common location by allathletes and burdensome coordination of schedules. If one or more teammembers are not able to attend at the common place and time, trainingfor full-team coordination cannot occur. (3) A training space mustaccommodate the bulk of the team trainer, whose maximum dimension, foran N-person trainer, will be on the order of N times that of asingle-person trainer. (4) Realistic team trainers are significantlymore costly on a per-athlete basis than individual trainers.

Techniques are therefore desired by means of which exercise machines canenable one or more athletes to receive realistic training on thecoordinative aspects of their sport without requiring multiple athletesto assemble at a single location. Moreover, there is need for suchexercise systems to be affordable and compact.

BRIEF SUMMARY Technical Problem

Exercise machines constructed according to the prior art are generallyprovided with energy dissipation (i.e., load) devices that employfriction, gaseous, and/or liquid damping effects and whose rate ofenergy dissipation is approximately fixed after an initial adjustment,e.g., throughout a given exercise session. Also, such exercise machinesgenerally include limited damping variability. Also, such exercisemachines (herein also termed “trainers”) are either inherentlysingle-user (i.e., lack means of communication with other exercisemachines that can be used to provide a common or “team” experience foroperators), or, in order to provide a common experience for operators,require that multiple machines be mechanically ganged into a relativelylarge multi-user assembly and that operators assemble at a singlefacility for the use of such a multi-user assembly. Moreover, simulatedreal-time competition between such assemblies would require theco-location of multiple assemblies, typically an expensive andimpractical proposition. For these and other reasons, improvements toexercise machines are desired.

Solution to Problem

Various embodiments of the disclosed apparatus and systems transcend thelimitations of the prior art by enabling athletes on separate exercisemachines, which may be far distant from each other, to exercise jointlyin a manner that approximates the experience of exercising jointly on areal physical apparatus (e.g., rowing shell). Moreover, variousembodiments of the disclosure enable athletes to train with or againstsimulated athletes. Some other advantages offered by embodiments of thedisclosure shall be made clear hereinbelow both descriptively and withreference to the Figures.

Various embodiments replace the dissipative mechanism of the prior artwith an electrical machine (generator) whose power output is dissipatedlargely by a resistive electrical load. Various embodiments compriseadditional computational, communicative, and other aspects. In variousembodiments, one or more computational aspects collect measurementinformation telemetrically from portions of the exercise machine; issuecommands to controllable aspects of the exercise machine (e.g.,electrical machine, resistive load); and communicate informatically(e.g., through a network) with various devices that can include, but arenot necessarily limited to, one or more of (1) other exercise machines,(2) a server that can gather and store data pertaining to multipleexercise machines and their operators and coordinate the behaviors ofmultiple exercise machines, (3) other computing devices, includingdevices operated by one or more coaches and/or by team participants withdistinctive roles (e.g., coxswains), and (4) sources of physiometricinformation such as wearable athletic monitors or activity trackers. Thecomputational aspects of various embodiments include softwarecapabilities for (1) calculating and recording the performance of teamsand individual operators, (2) rating and otherwise analyzing operatorand team performance, (3) algorithmically modeling combinations of oneor more operators, who may be at disparate physical locations, into oneor more “virtual teams” whose members' efforts affect the loadsexperienced by the one or more operators in a manner that simulatesjoint effort applied to a specific apparatus (e.g., a rowing afour-person scull), (4) numerically simulating the efforts (e.g.,oarstroke timing, power, and duration) of one or more “simulatedoperators” and the effects of these efforts on the loads experienced byreal operators and by other simulated operators, and (5) calculating theperformance of combinations of real and simulated operators so thatindividual operators may train as part of a complete team, or a partialteam may train as part of a complete team, or one virtual team (entirelyreal or partly or entirely simulated) may compete against one or moreother teams (entirely real or partly or entirely simulated). Theperformance characteristics of a simulated operator constitute a set oftunable parameters that may be based on the measured characteristics ofa real operator, selected from a library, custom-specified, randomlygenerated, or otherwise specified.

Also, various embodiments comprise devices that offer audiovisualfeedback to operators that can supplement the feedback supplied by themechanical load of the exercise machine: for example, a rowing-machineoperator may face a device that gives visual and/or aural cues such asan audiovisual representation of a lead rower, the sound of a coxswain'svoice (real or simulated), scenery to providing a visual indication ofmotion, performance metrics (e.g., stroke rate, operator power output),and the like. It may be beneficial for the audiovisual feedbacks offeredto multiple operators training as a team to be coordinated by acomputational device so that operators are offered consistent cues.Audiovisual feedback is in some embodiments provided to the operator bya virtual reality device (e.g., Oculus Rift) to endow the trainingexperience with a high degree of psychophysical realism. In one example,rowers on a virtual crew team—every one of whom is hundreds ofkilometers away from every other—share a virtual reality in which eachoperator occupies a definite point of view in a virtual watercraft, andmovement of the virtual watercraft (and potentially of competing virtualwatercraft) in the virtual reality is determined algorithmically fromthe physical efforts of the operators.

In various embodiments, the disclosed apparatus comprises an electricalmachine (e.g., a linear or rotary electrical generator) that ismotivated by one or more operators and supplies power to a load (e.g., abank of resistors). Regarding the provision of load for the operator,the electrical machine and its load bank correspond approximately to thedissipative load mechanism of an exercise machine built according to theprior art. Such prior-art dissipative mechanisms include (1) pistonmechanisms, whereby load is presented by hydraulic cylinders attached tohandles, and (2) braked flywheel mechanisms, wherein load presented by aflywheel braked using friction pads, electromagnets, air fins, waterpaddles, or other dissipative contrivances. In various embodiments ofthe disclosure, a linear electrical machine is employed in a manneranalogous to a resistive hydraulic cylinder, or a load-feeding rotaryelectrical machine is employed in a manner analogous to a flywheel load.

In various embodiments, the load that dissipates power generated by theelectrical machine can comprise one or more resistors that dissipateenergy as heat. The one or more resistors of the electrical load areherein collectively termed “the electrical load bank.” In one example,the net resistance of the electrical load bank is fixed and the currentthrough the load bank is varied in proportion to the required load.Alternatively, the net resistance of the electrical load bank isadjustable by means of signals transmitted from the system controller:e.g., relays may connect or disconnect resistors in the electrical loadbank, thus increasing or decreasing the mechanical load presented to theoperator. Additionally or alternatively, the electrical load bank maycomprise continuously variable resistive elements (e.g.,potentiometers). Non-electrical loads such as friction brakes andfluid-stirring mechanisms may be comprised by various embodiments,additionally or alternatively to resistive and other electrical loads.

In various embodiments that comprise a flywheel and a separately excitedalternator as the rotary electrical machine, the flywheel is coupled bya transmission mechanism (e.g., gearbox, common axis, or sprocket androller chain) to the rotary electrical machine, which the flywheeldrives. The torque T_(elec) of the alternator is determined by themutual inductance L_(af) (between the alternator's armature and fieldcircuit, by the alternator's armature current I_(arm), and by thealternator's field circuit current I_(fld). An electrical load bank(resistance R) is in series with the alternator's armature circuit.Thus, T_(elec), which contributes to the load encountered by theexercise-machine operator, may in such embodiments be adjusted byaltering at least one of R, I_(arm) and I_(fld).

Additionally or alternatively in various embodiments, components of arotary electrical machine may be weighted so as increase the electricalmachine's moment of inertia, enabling the electrical machine to act asan additional flywheel or as the system's sole flywheel. Moreover,additionally or alternatively, the flywheel and/or rotary electricalmachine may have a controllable moment of inertia (e.g., may incorporatedevices that move mass toward or away from the axis of rotation).

Herein, the terms “user,” “operator,” and “athlete” are usedinterchangeably.

Advantageous Effects

Various embodiments of the disclosure combine load control withnetworked communications and model-based control of loads to transcendshortcomings of the prior art. The ability of various embodiments tocombine operators at a single location or multiple locations into one ormore virtual teams, each of whom experiences a varying load thatrealistically approximates the experience that would be had in a sharedphysical setting (e.g., in a boat on the water, or in a multi-usertrainer with load linkage), overcomes the prior art's requirement thatteam members assemble at a common location to practice the coordinativeaspects of their sport. Since individual machines are linkedinformatically, not mechanically, if all team members do assemble at acommon time and place there is no need to find room for a largemulti-unit assembly, as in the prior art, in order to exercise in alinked manner: in an example, rowing machines scattered about a room canoperate as a multi-unit trainer.

As shall be made clearer with reference to the Figures, certainfunctions offered by some embodiments of the disclosure are entirelynovel as compared to the prior art. In an example, in variousembodiments a single operator may practice as a member of a team whoseother members are all simulated. In further examples, multiple operatorsmay, regardless of their physical locations, (1) practice together as acomplete team with realistic performance/load linkage, (2) practice witha combination of real operators and simulated operators (e.g., if thereare not enough real operators to form a complete team, the teamcomplement may be filled out by simulated operators), (3) be combinedvariously by a user (e.g., coach) into alternative team lineups, withoutany need for the operators to change locations or even get off theirmachines, and (4) compete with real or simulated teams regardless of thelocation of any operators. Moreover, the physics of different phases ofteam effort can be simulated by appropriate manipulation of exercisemachine loads (e.g., higher loads during acceleration; in rowing orbiking, higher values for water and/or air resistance loads at highervelocities; in rowing or biking, higher loads when going against acurrent or biking uphill, respectively). In a further example,embodiments of the disclosure can both enhance training for traditionalteam rowing and expand the established sport of competitive indoorrowing in ways that will be clear to persons familiar with these sports.

These and other objects, along with advantages and features of thedisclosure, will become more apparent through reference to the followingdescription, the accompanying drawings, and the claims. Furthermore, itis to be understood that the features of the various embodimentsdescribed herein are not mutually exclusive and can exist in variouscombinations and permutations. Furthermore, the particular features,structures, routines, steps, or characteristics may be combined in anysuitable manner in one or more examples of the technology. Also,although single-user trainers are frequently referenced herein,multi-user trainers may be similarly incorporated in embodiments of thedisclosure. All such variations are contemplated and within the scope ofthe disclosure.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other aspects of the present disclosure will becomeapparent to those skilled in the art to which the present disclosurerelates upon reading the following description with reference to thefollowing figures:

FIG. 1 is a schematic representation of a single-user exercise systemaccording to one form of the prior art;

FIG. 2 is a schematic representation of an illustrative exercise systemaccording to at least one aspect of the present disclosure;

FIG. 3 is a schematic representation of at least one embodiment of thepresent disclosure showing the addition of a retrofit kit to theexercise system of FIG. 1 for conversion to the exercise system of FIG.2;

FIG. 4A is a schematic representation of an exemplary decentralizednetwork comprising a number of exercise systems, each similar to theexercise system of FIG. 2;

FIG. 4B is a schematic representation of an example four-member team inthe network of FIG. 4A;

FIG. 5 is schematic representation of an exemplary centralized networkcomprising a number of exercise systems, each similar to the exercisesystem of FIG. 2;

FIG. 6A is a side view of an example exercise system of FIG. 2; and

FIG. 6B is a schematic representation of the exercise system of FIG. 6Aincluding additional components.

DESCRIPTION OF EMBODIMENTS

In the Figures and discussion thereof, systems and methods are disclosedthat enable the construction of an exercise machine which improvesaspects of individual and team training. These systems and methods canprovide networked communication between multiple exercise machines toprovide machine users with a common exercise experience that simulatesaspects of joint operation of a single athletic apparatus or ofoperation in a common environment of separate athletic apparatuses. Thetypes of exercise machine to which these systems and methods applyinclude, but are not limited to, rowing machines, stationary bicycles,elliptical machines, and cross-country skiing machines. This disclosureprimarily describes illustrative cases in which the exercise machine isa rowing machine, but no restriction is intended by this usage. In theFigures, for the sake of clarity, certain features are omitted whosenecessity or utility would be clear to persons familiar with the designand operation of exercise machines and other relevant devices; forexample, detailed provisions for wiring an alternator or for plugginginto mains power are not depicted, and force transmission mechanismsstandard to various exercise machines are not depicted. The emphasis ofthe Figures is on features that clarify embodiments of the disclosure.

FIG. 1 schematically depicts portions of an illustrative single-userexercise system 100 according to one form of the prior art. A user orathlete 102 operates an exercise machine 104. The exercise machine 104comprises a force mechanism 106, an inertial mechanism 108, and adamping mechanism or load 110. The force mechanism 106 transmits forcesbetween the body of the athlete 102 and other portions of the exercisemachine 104: in an example, in a stationary bicycle the force mechanism106 comprises seat, handlebars, pedals, sprocket, chain, and othercomponents. In another example, in a rowing machine the force mechanism106 comprises seat, foot stretcher, handle, and other components. Theinertial mechanism 108 typically comprises a flywheel, and smoothsoperation of the exercise machine by simulating the inertia of anathlete moving with a mobile athletic apparatus (e.g., cyclist onbicycle, rower on watercraft). The load 110, which is typicallyadjustable, simulates dissipative and possibly other loads experiencedby an athlete moving an athletic apparatus (e.g., resistance of airand/or water, friction, uphill travel). The schematization or breakdownof a typical exercise system 100 shown in FIG. 1 is offered to clarifysubsequent Figures and discussion, but is to some degree arbitrary, andother schematizations are possible.

FIG. 2 schematically depicts portions of an illustrative exercise system200 according to an embodiment of the present disclosure. An athlete 202operates an exercise machine 204. The exercise machine 204 comprises aforce mechanism 206, an inertial mechanism 208, an electrical machine210 (e.g., linear or rotary generator), a damping mechanism or load 212,a computer device 214, and a user interface device 216. In variousembodiments, the electrical machine 210 can be any suitable deviceincluding, but not limited to, a separately excited electric machine,alternating current induction motor, permanent-magnet alternatingcurrent motor, or brushed or brushless direct current motor. The forcemechanism 206 transmits forces between the body of the athlete 202 andother portions of the exercise machine 204. The inertial mechanism 208can comprise a flywheel. The electrical machine 210 is coupled to theinertial mechanism 208 by a transmission mechanism (not shown) andconstitutes a mechanical load on the inertial mechanism 208. In variousembodiments, the inertial mechanism 208 and electrical machine 210 areintegrated into a single device (e.g., a rotary electrical machine withan appropriately high moment of inertia).

The load 212 comprises an electrical load which serves to dissipate orabsorb electrical energy produced by the electrical machine 210. In oneexample, the electrical load is adjustable in magnitude. In variousembodiments, the load 212 comprises resistors, a battery, an AC/DCconverter and/or a DC/DC converter, and various electrically poweredcomponents of the exercise machine 204 or of other devices.

The user interface 216 comprises one or more of audio, visual, andtactile means of conveying information to the athlete 202, where suchinformation can comprise metrics of athlete performance (e.g., strokerate, power output), athlete biometrics (e.g., heart rate), audiovisualrepresentations or simulations (e.g., virtual reality), audio (e.g.,voice, rhythm cues), and others. The user interface 216 also comprisesone or more means of information input from the athlete 202 (e.g., voiceinput, keyboard input, touchscreen input, eye-movement basedinteraction, etc.).

The computer 214 comprises a data-gathering capability, computationalcapability, control capability, communications capability, and memorycapability. The data-gathering capability of the computer 214 receivessignals from sensors (not shown) communicating with various portions ofthe exercise machine 204. In FIG. 2, dashed arrows denote informatictransmission paths (as distinguished from mechanical and electricalenergetic transmission paths, denoted by solid arrows). Thus, thecomputer 214 receives sensed information from and transmits (via itscontrol capability) controlling commands to the force mechanism 206,inertial mechanism 208, electrical machine 210, load 212, and interface216. The control capability of the computer 214 enables it to commandchanges in the states of various components of the exercise machine 204.For example, the computer 214 may transmit signals that cause theexcitation current in a winding of the electrical machine 210 toincrease or decrease, thus altering the torque placed by the electricalmachine 210 on the inertial mechanism 208 and ultimately altering themechanical load felt by the athlete 202. In another example, thecomputer 214 transmits signals that cause a resistive component of theload 212 to increase or decrease, altering the load on the electricalmachine 210 and ultimately altering the mechanical load felt by theathlete 202.

The communications capability of the computer 214 enables it to exchangeinformation with a network 230. The communications capability is capableof information exchange through one or more wired channels andprotocols, one or more wireless channels and protocols, or both. In anexample, the network 230 comprises a number of exercise machines thatare similar to exercise machine 204 and are interconnected by cabled orwireless channels, where machine 204 and the machines with which it isin communication act as communicative nodes in a network topology. Inanother example, the network 230 is the internet. Through the network230, the computer 214 can be in informatic communication with machinessimilar to exercise machine 204, general computing devices, and otherdevices capable of informatic exchange through the network 230. In anexample, the exercise machine 204 communicates through the network 230with a wearable sensor device worn by the athlete, acquiring biometricinformation (e.g., heart rate) and utilizing such information in thecomputation and memory capabilities of the computer 214.

The exercise machine 204 can be in communication via the network 230with M−1 other, similar exercise machines (best represented in FIG. 4A),which are typically also in communication with each other. Together, theexercise machine 204 and the M−1 exercise machines with which it is innetworked communication constitute a networked group of M exercisemachines. The quantity of members of a networked group may vary fromoccasion to occasion.

As shall be made clear with reference to illustrative embodimentshereinbelow, the computational capability of the computer 214 implementsa computational algorithm, herein termed the “team algorithm.” The teamalgorithm accepts as numerical inputs measured electrical and mechanicalquantities from portions of the machine 204 (e.g., rotational velocityof a flywheel, acceleration of a flywheel, voltage across a resistiveload, current in a generator winding). These measured quantities aresuch as enable estimation of the real-time effort exerted by the athlete202 and, potentially, of other quantities. The team algorithm alsoaccepts as inputs a number of numerical parameters stored in the memorycapability of the computer 214. These parameters can express physicalproperties of a hypothetical apparatus (e.g., a particular type ofwatercraft), physical characteristics of a given exercise machine (e.g.,the moment of inertia of a flywheel), physical characteristics ofathletes (e.g., mass), and other variables. The team algorithm can alsoaccept as input real-time data representing the activities of Nathletes, N≥1, one of whom may be the operator 202 of the exercisemachine 204. The N athletes whose activity data are inputted to the teamalgorithm are herein said to constitute a “virtual team.” Activity datamay be derived from the activities of real human athletes, ornumerically generated, or both: that is, some or all of the N networkedathletes on a virtual team may be real athletes and some or all may besimulated athletes. Simulation of an athlete is performed by codecomputed by the computer 214 or by some computer device with whichcomputer 214 is in communication via the network 230. Simulation can bebased on parameters derived by measurement from real athletes orotherwise derived, and may include a random aspect (e.g., the efforts ofa simulated rower may vary slightly in a realistically nondeterministicfashion from stroke to stroke). If M real athletes on M real machinesare participating in an N-member virtual team, then N−M team members aresimulated.

Data received by the computer 214 via the network 230 during computationof the team algorithm typically include real-time data on the activitiesof the M−1 real athletes other than the real local athlete 202 on thevirtual team. Real-time data on the activities of the real local athlete202 are gathered directly by the computer 214 from machine 204. Also,the computer 214 typically transmits activity data on the local athlete202 via the network 230 to the M−1 machines from which the machine 204is receiving athlete activity data. Data on the activity of simulatedathletes on a virtual team may be produced locally by the computerdevices of exercise machines (e.g., computer 214), or communicated to oramong exercise machines or computers via the network 230, or both.

The team algorithm computed by computer 214 produces commands that arecommunicated to various controllable mechanisms of the machine 204(e.g., aspects of the electrical machine 210 and load 212), ultimatelyaltering the mechanical load experienced by the athlete 202. The M−1other networked machines similarly compute the team algorithm tocalculate commands for their own mechanisms, thus affecting theexperiences of their own operators in a manner coordinated with that ofmachine 204. That is, the M machines of the M real athletes on anN-member virtual team all possess or receive activity information for Nathletes and compute load adjustments for the N athletes. For the Mmachines of the virtual team operated by real athletes, physical loadadjustments are actually made; for the N−M simulated athletes,adjustments can be made to the simulation calculations, appropriatelyaltering the effort data corresponding to each simulated athlete. Themethod of measurement, calculation, and apparatus adjustment hereindescribed constitutes a form of closed-loop control.

The team algorithm, operating on real activity data from M real athletesand simulated activity data from N−M simulated athletes, andconsequently modifying the loads specified for both real and simulatedathletes on an N-member team, is designed to approximate the performanceof an actual athletic apparatus (e.g., rowboat) operated jointly by theN team members. By altering the parameters of the team algorithm, thephysical responses of various apparatuses may be simulated (e.g.,4-rower craft of a first type, 4-rower craft of a second type, 8-rowercraft). Real athletes participating in a virtual team experiencetime-varying resistance from their exercise machines that reflects theefforts of other team members, real and simulated, in a mannerapproximating joint team operation of a real physical apparatus, eventhough other real team members are operating physically separatemachines that may be geographically distant. In an example, the exercisemachine 204 is a rowing machine and the athlete 202 is a rowerparticipating in a virtual team rowing a virtual four-person scull. Theresistance presented by the handle or oar to athlete 202 will varythroughout each stroke and from stroke to stroke in a manner thatdepends via the team algorithm on the timing, power, and other featuresof the strokes of athlete 202, on the strokes of the other threeathletes on the team, and on the characteristics of the watercraft modelchosen as the virtual apparatus (e.g., four-person scull).

Moreover, the outputs of the operator interface 216 are typicallyaltered in coordination with team performance as determined by the teamalgorithm. In an example, the interface 216 comprises a virtual-realityheadset, the virtual apparatus simulated is a four-rower watercraft, aparticipating athlete 202 experiences a visual field with coordinatedaudio placing them in a specific position in the virtual watercraft in agiven water environment, and the watercraft is seen by the athlete 202to move through its environment in a manner dependent on the team'sjoint efforts. One or more competing virtual watercraft may berepresented in the perceived environment, either simulated or partly orwholly rowed by real athletes, and real competing athletes may besupplied with complementary points of view in the virtual reality.Quantitative data on individual performance, team performance,competitor performance, and other variables can be made selectivelyavailable (e.g., visually) to individual athletes, coaches, teams, andothers. Audio, video, and other data gathered from athletes and otherparties (e.g., coaches, onlookers) may be integrated variously with theoutputs of the operator interface 216 to produce virtual settings ofvarying character, interactivity, and realism, enabling the training ofathletes in the psychosocial as well as physical aspects of a sport.Sport onlookers may be linked to the system through virtual-realityheadsets, enabling audiences to be virtually present at virtual racesrowed by real and/or simulated athletes, where all onlookers and realparticipants may be separated geographically to any degree. Other formsof interface coordination, e.g., coach audio shared simultaneously toall athletes on a virtual team, are also contemplated and within thescope of the disclosure. All such applications, however elaborate,depend on the capability of various embodiments of the disclosure tomechanically produce for each individual exercise-machine user anexercise experience that reflects both that machine user's efforts andthe simultaneous efforts of other users, real and/or simulated.

It is possible to apply the described apparatus and methods to othertypes of exercise machines. In an example, the exercise machine 204 ofFIG. 2 is a stationary bicycle that can simulate real-world loadconditions of various topographies, drafting effects from differentlocations in a riding pack, tandem riding, etc., whether for a singlerider or simultaneously for members of a team using a networked group ofsimilar exercise machines. In another example, the exercise machine 204is a cross-country ski machine that can simulate various topographies,wind conditions, snow types, etc. In general, any suitable type ofexercise machine can employ the described apparatus and methods toenhance group workouts and to enable the use of customized, possiblytime-varying load profiles for individual workouts.

The advantages of embodiments of the disclosure may, in some instances,be realized by modifying or retrofitting an existing exercise machinebuilt according to the prior art. FIG. 3 depicts the retrofitting of anexercise machine 302 built according to the prior art with anillustrative “retrofit kit” 304. The machine 302 is, before retrofit,similar to the machine 104 of FIG. 1. The load mechanism of theprior-art machine 302, corresponding to the load mechanism 110 ofmachine 104 of FIG. 1, is removed and replaced by the retrofit kit 304,which comprises an electrical machine 306, load 308, computer 310capable of communicating with a network 230, and an operator interface314. The properties of the electrical machine 306, load 308, computer310, and interface 314 are as described above with reference tocorresponding components in FIG. 2. For retrofit to occur, anappropriate transmission mechanism (not shown) must in general exist orbe provided (e.g., as part of the kit) for linking the inertialmechanism 316 of the machine 302 to the electrical machine 306 of thekit 304. In an example, the inertial mechanism of a rowing machinecomprises a flywheel, the electrical machine 306 of the retrofit kit 304comprises a rotary electrical generator, and with appropriate attachmenthardware, a sprocket-and-chain transmission can be employed to link theflywheel to the generator.

Reference is now made to FIG. 4A, which schematically depicts anillustrative network 400 comprising a number of exercise machines (e.g.,trainer 402), each similar to the exercise machine 204 of FIG. 2. Forsimplicity, the network 400 comprises L physical locations (e.g.,gymnasia), each with K trainers (total N=L×K trainers), each trainerpotentially accommodating a single athlete. Ellipses indicate trainersnot explicitly depicted. In the topology of FIG. 4A, communicationpathways (e.g., pathway 404) enable each trainer to communicate with atleast one additional trainer. It is to be understood that FIG. 4A showsa limited number of exercise machine communication pathways for the sakeof clarity, but that in general each trainer in the network can beconnected to every other; further, it is a well-known mathematicalresult that the total number of possible communication pathways (onenode direct to another) in such an arrangement is N(N−1)/2. In theillustrative network topology of FIG. 4A, software running on thecomputational capabilities of the individual trainers enables thetrainers to communicate with each other and thus for the operators ofvarious trainers to associate with each other in one or more teams. Forexample, in FIG. 4A, the operators (e.g., athletes or rowers) oftrainers 402, 406, 408, and 410 (highlighted by heavier outlines) haveassociated into a four-member team. All four team members can now workout simultaneously on a common virtual apparatus (e.g., four-personscull); the load experienced by each team member will be adjusted inreal time, as a function of the efforts of all team members and thechosen load profile of the virtual apparatus, to approximate thesensation of engaging with a jointly operated physical apparatus. Thenetwork 400 may also be referred to as a simulation system or a crewtraining simulation system.

FIG. 4B depicts another example of a four-member team 414 in the network400 (best seen in FIG. 4A), for clarity showing only the trainers ofteam members and the communications pathways connecting them. Team 414consists of the operators of trainers 402, 406, 410, and the virtualoperator of a simulated operator trainer 416. The activity data ofsimulated trainer 416 can be calculated locally (i.e., redundantly) bythe computational capabilities of all three trainers 402, 406, 410 orcan be calculated by any one of the trainers 402, 406, 410 andcommunicated to the other two.

Another illustrative embodiment of a network with additional details andhaving a topology that differs from that of FIGS. 4A and 4B, isschematically depicted in FIG. 5. The illustrative topology of FIGS. 4Aand 4B is decentralized, whereas the illustrative topology of FIG. 5 iscentralized: additional architectures will be readily envisaged bypersons familiar with the art of device networking and control, and allsuch architectures are contemplated and within the scope of thedisclosure. The embodiment of FIG. 5 comprises a crew trainingsimulation system 500. The system 500 comprises some number N oftrainers with associated real operators, e.g., trainers 502, 504, 506.Ellipses indicate trainers not explicitly depicted. Trainer 502 istypical of the trainers comprised by the system 500. The computer device508 of trainer 502 runs a program (application, app) 510 termed the CrewApp. The program 510 implements the team algorithm (not shown), a userinterface 512 that governs interactions with the operator of the trainer502, a communications and media interface 514 that handles interactionswith the network 516 (which corresponds to the network 230 of FIG. 2),and other functions. In the illustrative system 500 of FIG. 5, thenetwork 516 is the internet and the computer device 508 communicateswith the network 516 via a standard wireless technology (e.g., WiFi,Bluetooth). The various trainers (e.g., trainers 504, 506) communicateindependently and simultaneously with the network 516; the number N oftrainers connected to the network 516 typically increases and decreasesover time as trainers are logged in and out of the system 500. In oneexample, only trainers occupied by operators will be logged in, i.e., inactive communication with the network 516. The trainers may communicatedirectly with each other through the network 516, or may communicatewith each other solely or primarily through the agency of a server 518,which is also in communication with the network 516. The server 518 canbe a computing device (e.g., laptop, desktop, tablet) capable ofoverseeing coordination of trainers, communications between trainers andoperators, simulation of team operation of virtual apparatuses, othersimulation tasks (e.g., virtual reality generation), and storage,retrieval, and generation of data pertaining to the operation of thesystem 500 (e.g., data pertaining the conduct of simulated training runsand competitions). In various embodiments, the server 518 is not aunitary computing device (e.g., laptop computer); that is, itscomputational and data-storage capabilities may be realized by multipledevices, either redundantly or in a distributed (e.g., cloud-computing)manner, where such multiple devices may include the computer devicescomprised by the trainers. Thus, no restriction is intended by therepresentation of the server 518 as a unitary device in FIG. 5. Theserver 518 comprises a database layer 520 that implements access to oneor more databases, e.g., an operators database 522 (recordinginformation pertaining to individual operators, both real andsimulated), a coaches database 524 (recording information pertaining tocoaches or other coordinative system users), an apparatus database 526(containing information pertaining to virtual apparatuses), andpotentially other databases 528, indicated in FIG. 5 by ellipses, whichmay contain any data deemed pertinent to the conduct of the system 500(e.g., measured mechanical characteristics of individual trainers,outcomes and statistics pertaining to simulated races).

The server 518 comprises software programs that implement variousfunctional aspects of the system 500. These programs can include adatabase app 530, which maintains the contents of the database layer 520and retrieves information for serving to trainers and other devices asneeded; a simulation app 532, which calculates the team algorithm,calculates the activities of simulated operators, and performs othercalculative tasks; an administrative app 534, which enables a masteruser to act at an operations management level; a developer app 536,which enables access to the application programming interfaces of thesystem for application development; and a root app 538, which enablesmaster control over other user categories and access to everythingcontained in the database layer 520. In various embodiments, thefunctions realized in the illustrative system 500 by the database layer520 and the apps 530, 532, 534, 536, and 538 are realized by adifferently organized set of applications or software modules. Moreover,the system 500 can comprise one or more additional computing devices,e.g., a coach device 540 supplying authorized access to a “coach,” i.e.,user having coordinative, administrative, or oversight powers. The coachdevice 540 may in various embodiments or modes of operation of system500 be the computer device of one of the trainers (e.g., trainer 502), alaptop or desktop, or a mobile computing device. The network 516 mayalso communicate with other networks and with devices connected thereto.

In an illustrative mode of operation of system 500, a coach device 540,communicating with the server 518, is authorized to work with somesubset of the N trainers logged on to the system 500. For example, thecoach device 540 may be one of a limited number of coach devices at auniversity authorized to access the system 500 as part of a paidsubscription service. The user of coach device 540, employing a softwarecapability running on their computer device, chooses the operators of Ptrainers, a subset of the N trainers, to be members of a virtual team.The user of the coach device 540 also specifies a specific virtualapparatus and, potentially, other conditions that will influence theload profile of the run (e.g., race topology, wind conditions, raceduration). The server 518 sets up a computational model (e.g., teamalgorithm) with parameters set and/or updated during simulation toreflect the choices transmitted by the coach device 540 and otherpertinent variables (e.g., trainer-specific mechanical characteristics)and employing also as inputs activity data from the P team members. Therun begins on a signal from the coach device 540 or at a set time,whereupon activity data from the P trainers begins to be transmitted tothe server 518 through the network 516. The server 518 computationallymodels the behavior of the virtual apparatus based on its variousparameters and the activity data received and transmits instructions foreach of the P trainers accordingly to modify the loads experienced bythe trainer operators (e.g., by increasing or decreasing the current toa generator winding). The run terminates at another signal or time. Theserver 518 records in its database layer 520 all data received orgenerated by the server 518 during the course of the run, which mayinclude activity data from the trainers, operators' physiometric datathat may have been transmitted through the network 516 from activitymonitors, race outcomes, and the like.

The topology of FIG. 5 requires on the order of N communicativechannels, as opposed to the N(N−1)/2 channels of the topology of FIG. 4.

The number of distinct virtual teams that can be assembled using eitherthe topology of FIG. 4A or of FIG. 5 grows rapidly with N. By thebinomial theorem, the number of possible teams of size P that can bespecified from N operators without regard to order (i.e., the number ofcombinations of size P) is given by the binomial coefficient,N!/(P!(N−P)!). However, in many sports team-member ordering does matter(e.g., it matters where crew members are seated in a boat); in suchsports, the number of teams of size P that can be specified from Noperators with regard to order (i.e., number of permutations of size P)is N^(P). Thus, embodiments of the disclosure enable athletes, includingboth athletes at a single facility and athletes at widely separatedfacilities, to be rapidly and easily combined and recombined in apotentially very large number of virtual teams of various sizes,exercising on virtual apparatuses and in virtual environments ofpractically unlimited number. This capability is not offered inpracticable form by the prior art (which requires athletes to assembleat a common location to practice as a team, and to jointly operate largemulti-user training apparatuses, or actual athletic apparatuses in thefield, to train as a team). The combinatoric team-forming capability ofembodiments of the disclosure offers many advantages: e.g., a coach caneasily try out a number of team permutations to see which is the mostcompetitive under specified environmental conditions, using specifiedathletic apparatuses, and so on.

In another illustrative mode of operation of system 500, more than onevirtual team may be assembled at a time, by one or more coaches, fromamong the N available trainers (assuming sufficiently large N) and setto compete against each other in a virtual race. The simulation of eachteam's run may occur independently of the simulation of each otherteam's run, or the simulation app 532 may comprise provisions formodeling interactions of teams in a virtual environment.

In yet another illustrative mode of operation of system 500, one or moreteam members of one or more virtual teams may be simulated by the server518. At one extreme, all participating athletes are real and nosimulated athletes are employed; in various mixed cases, one or morereal athletes and one or more simulated athletes are employed; and atanother extreme, all athletes are simulated. The latter mode ofoperation of system 500 may be used for training of coaches, forinvestigation of various styles of team formation and competitiontactics, and other purposes.

FIG. 6A schematically depicts in side view portions of an illustrativeembodiment of the disclosure comprising a rowing machine 600. The rowingmachine 600 is operated by a rower 602 and comprises a sliding seat 604,a foot stretcher (brace) 606, a handle 608, a connective structure 610(only partly depicted), a user interface device 612, and a protectivehousing 614. The rowing machine 600 also comprises, inside theprotective housing 614, a flywheel 616, a generator 618, a firstsprocket 620 attached to the flywheel 616, a loop chain 622, a secondsprocket 624 attached to the generator 618, an electrical load bank 626,wiring 628 conveying electrical power from the generator 618 to theelectrical load bank 626, a fan 630 that cools the electrical load bank626, and a computer device (controller) 632. The controller 632 isequipped with a wireless communication capability 634 (e.g., WiFi orBluetooth) that enables the controller 632 to communicate, through anetwork (best seen in FIG. 5) with other devices (best seen in FIG. 5),e.g., rowing machines similar to machine 600 or various computingdevices connected to the network, such as a server. The handle 608 andconnective structure 610 (a pullable cord or chain) communicate via astandard force-transferring mechanism (not shown) with the flywheel 616,enabling a force generated by the rower 602 to urge the motion of theflywheel 616 (i.e., during performance of an oarstroke). That is, therower 602, by pulling on the handle 608, applies a torque T_(athlete) tothe flywheel 616. The resistance of the flywheel 616 to acceleration isdetermined by its moment of inertia and by any retarding torque appliedto the flywheel 616, e.g., torque applied via the sprocket 620. Thus,for example, the electrical generator 618 communicates a torque load tothe flywheel via sprocket 624, chain 622, and sprocket 620, increasingthe resistance to acceleration of the flywheel 616. Increased resistanceto acceleration of the flywheel 616 is felt by the rower 602 asincreased pulling resistance.

The rowing machine 600 is illustrative: other configurations, which willbe known to persons having skill in the art, are possible. In theillustrative embodiment of FIG. 6A, the generator 618 is an alternator.Various sensors, wires, and other components of the machine 600 are notdepicted in FIG. 6A for the sake of clarity.

Referring again to FIG. 6A, one particular example of the exercisemachine 600 can be a rowing machine as described above. The exercisemachine 600 includes a cyclical actuator 608, which can be a handle. Inone example, the handle can be configured to replicate a handle of anoar used on a typical watercraft, such as a multi-rower shell. Thecyclical actuator 608 is movably mounted to the exercise machine 600.

Referring again to FIG. 6A, an illustrative example of an exercisemachine according to this disclosure can be a rowing machine 600 asdescribed above. Components corresponding to some parts of theillustrative machine 600 can be comprised by exercise machines accordingto various other embodiments of the disclosure as follows. The handle608 of FIG. 6A can be generally understood as a cyclical actuator, whichcan take various forms in various embodiments. In one example, a cyclicactuator is configured to replicate a handle of an oar used on a typicalwatercraft, such as a multi-rower shell. In general, the cyclicalactuator is movably coupled via a connective structure to the exercisemachine (e.g., rowing machine 600).

Various exercise machines according to the disclosure include mechanicalenergy storage devices, e.g., flywheel 616 of machine 600. (Mechanicalenergy is stored in all moving components of an exercise system,including the athlete, but herein the phrase “mechanical energy storagedevice” refers to a device whose primary function is to store mechanicalenergy.) In the example of FIG. 6A, the mechanical energy storage deviceis the flywheel 616 mounted to the exercise machine 600: the connectivestructure 610 (cord) operatively connects the cyclical actuator 608(handle) to the mechanical energy storage device 616 (flywheel).

It is to be understood that the mechanical energy storage device caninclude structures other than the flywheel 616. For example, a motorthat has sufficient inertia may act as both the flywheel 616 and theelectrical generator 618. Other mechanical energy storage devices arealso contemplated.

In various embodiments, this relationship of parts (cyclic actuator,connective structure, mechanical energy storage device) can be realizedby various mechanisms. In an example, any suitable connective structurecan be used (e.g., strap, cord, chain, lever, friction wheel, pedalcrank arm) that provides a physical connection between the cyclicalactuator (e.g., handle, pedal, ski) and the mechanical energy storagedevice (e.g., flywheel, spring, moveable weight, moving fluid). In oneexample, a connective structure can be configured to be actuated like anoar on a watercraft. In another example, a connective structure can beplaced directly in front of the operator and pulled rearward as shown inFIG. 6A. Other examples of connective structures include multiplecomponents and combinations of components such as gears, shafts, axles,jointed rods, etc. Regardless of the physical make-up of the connectivestructure, the connective structure transfers and/or transforms a forcegenerated by an operator of the exercise machine in such a manner thatmotion of the cyclical actuator urges motion of the mechanical energystorage device (e.g., rotation of a flywheel).

In an illustrative class of rowing machines according to someembodiments of the invention, the connective structure includes an upperaxle. The upper axle can be operably connected to the cyclic actuator(i.e., handle) directly or via portions of a connective structure suchthat the rowing action of an operator urges the upper axle to rotate.The upper axle is mounted to the flywheel such that rotation of theupper axle urges the flywheel to rotate. A transmission mechanismconnects the flywheel to a lower axle connected to an electricalgenerator. The individual components of the handle, the connectivestructure, the flywheel, the two axles, and the transmission mechanismcoupling the two axles can be collectively thought of as a drivetrain totransmit motion from the operator to an electrical generator. In thisexample and in various other embodiments, the electrical generator 618can be any suitable device including, but not limited to, a separatelyexcited electric machine (SEPEX), alternating current (AC) induction,permanent-magnet alternating current (PMAC), brushless direct currentmotor (BLDC), etc. Additionally, the described components are but oneexample of a drivetrain, and any suitable means of transferring motioncan be employed by exercise machines according to various embodiments ofthe disclosure.

Continuing discussion of the foregoing example, an exercise machine(e.g., machine 600 of FIG. 6A) in the illustrative class of machinesexercise machine comprises an electrical generator 618 having arotatable shaft that is connected to the lower axle. The rotatable shaftof the electrical generator 618 is the lower axle. The electricalgenerator is operatively connected to the flywheel 616 through thedrivetrain such that rotation of the upper axle and/or the flywheel 616urges rotation of the rotatable shaft in the electrical generator 618.Rotation of the motor on the generator shaft creates an electricalsignal. In some members of the illustrative class of machines, theelectrical generator 618 is an alternator which creates an electricalsignal that is AC, which can be converted to a direct current (DC). Itis to be noted that any suitable electrical generator can be used invarious embodiments comprising an electrical machine. Also, exercisemachines in the illustrative class of machines according to variousembodiments can include a converter (e.g., a rectifier) in electricalcommunication with the electrical generator 618 and a resistive loadbank 626. In one example, the converter converts the AC electricalsignal delivered from the alternator to DC electrical signal that ispassed to the electrical load bank. In other members of the illustrativeclass, the converter can be integral to the alternator such that thealternator delivers a DC electrical signal output.

In an exemplary member of the illustrative class, the resistive loadbank 626 is configured to supplement the load resistance of the flywheel616. The resistive load bank 626 is in electrical communication with theelectrical generator 618. The resistive load bank 626 can be consideredpart of the “armature circuit.” In another exemplary member of theillustrative class of machines, a wire harness delivers the electricalsignal from the electrical generator 618 to the electrical load bank 626and the electrical signal is dissipated at the electrical load bank 626,typically by generating heat. In one example, heat generated in theelectrical load bank 626 can be dissipated using at least one fan 630.The rate of fan speed can be proportional to the average electrical loadthrough the electrical load bank 626.

Additionally, the electrical load bank 626 can comprise variousdifferent structures to achieve the goal of dissipating the electricalenergy created by physical work by the rower 602 input into theelectrical generator 618. In one example, the electrical load bank 626can comprise a series of resistors that dissipate at least a portion ofthe electrical signal created by the electrical generator 618. Inanother example, the electrical load bank 626 can comprise a combinationof resistance elements and capacitance elements. In yet another example,the electrical load bank 626 can comprise thermo-electric generators.The thermo-electric generators can beneficially decrease the overallsize of the electrical load bank 626 and provide electrical cooling tothe electrical load bank 626.

The operative organization of rowing machine 600, which is typical of anumber of rowing machines according to various embodiments of thedisclosure, is schematically clarified in FIG. 6B, with the omission forclarity of control pathways from the controller 632 to the alternator618, load bank 626, and other components, and with the addition ofseveral components comprised by various embodiments but not depicted inFIG. 6A. In particular, as shown in FIG. 6B the power output of thealternator 618 may be passed through an electrical converter 636. Theelectrical converter 636 can include an AC/DC converter and/or a DC/DCconverter, and the resulting DC power may be dissipated in the load bank626 and/or used to charge a battery 638 (e.g., a twelve-volt,sealed-lead-acid battery or a fifteen-volt lithium-ion battery), hereunderstood to comprise an appropriate charging mechanism, which may inturn supply power to the controller 632, the user interface or displaydevice 612, one or more windings of the alternator 618, and possiblyother devices. By means of the electrical converter 636 and battery 638,the rowing machine 600 may be made self-powering as regards itselectrical devices. In various embodiments, the electrical converter 636can be integral to the alternator 618 such that the alternator 618delivers a DC electrical output signal. For simplicity, the illustrativeexercise machine 600 shown in FIG. 6A does not comprise a converter 636or battery 638.

Referring again to the illustrative machine 600 of FIG. 6A, provisionsare made (but, for clarity, not depicted in FIG. 6A) for acquiringmeasurement data of a number of operative variables of the exercisemachine 600, to be more particularly described below. These data areconveyed (e.g., by wiring) to the controller 632, which can use thesedata in cooperation with various tunable parameters and a team algorithmstored in a memory capability to compute the team algorithm. The outputsof the team algorithm are used by the controller 632 to alter the loadexperienced by the rower 602, as shall be described. For example, as therower 602 pulls the handle 608, this action moves the flywheel 616,which in turn rotates the alternator 618 to create an electrical signalthat is dissipated by the load bank 626. The algorithm calculated by thecontroller 632 can be used to simulate real-world conditions of variousrowing apparatuses including, but not limited to, a one-person scull,two-person scull, four-person scull, two-person sweep, four-personsweep, and eight-person sweep.

Discussion hereinbelow will first focus on the provision of a specificload profile to a user of isolated machine 600, that is, on a state ofoperation not incorporating activity data from other trainers or fromsimulated operators. Although this discussion refers for the sake ofspecificity and clarity to machine 600 of FIG. 6A, it will be clear topersons familiar with the science of engineering that the principlesthus clarified will, with appropriate adjustments, apply equally tovarious other embodiments.

First, it is to be noted that the effort produced by the rower 602 atany moment can be characterized by the instantaneous torque T_(athlete)exerted by the rower 602 on the flywheel 616 via the connectivestructure 610. The torque T_(athlete) may be considered under twoaspects, i.e., actual or measured T_(athlete) and targeted or desiredT_(load). Actual T_(athlete) is produced by the rower 602; targetedT_(load) is a numerically calculated quantity which the exercise machine600 will, in typical operation, proceed to produce in response to achanging state of the exercise machine 600. In general, the goal of arower is to row at a certain rate (which, in a team context, is ideallysynchronous with the rowing of team-mates): e.g., to produce a certainrate of acceleration, as during startup, or to maintain a certain speed,as during a cruising phase. Also, in the exercise machine 600, therotational velocity ω of the flywheel 616 is analogous to watercraftspeed: i.e., the angular momentum of the flywheel 616 turning at a givenω is analogous to the linear momentum of a crew-bearing watercraftmoving at a given velocity. Similarly, the effort (T_(athlete)) requiredto increase or maintain the rotational velocity ω of the flywheel 616 isdetermined by the moment of inertia J of the flywheel 616 and by anytorque loads on the flywheel 616, and this effort is analogous to thatrequired to increase or maintain the velocity of a watercraft, which isdetermined by the inertia of the watercraft and crew and by any fluiddrag on the watercraft. The function of the controller 632 can, in thiscontext, be stated as follows: To require of the rower 602, as the rower602 seeks to maintain a certain power output, an actual T_(load) thatmatches a calculated, target T_(load) reflecting hypothetical physicalconditions. These hypothetical physical conditions are determined by ahypothetical apparatus (e.g., boat type) moving in a hypotheticalphysical environment. Herein, we refer to a numerical characterizationof the apparatus and environment as a “load profile.” Thus, targetedT_(load) is in general a function both of a load profile and the stateof operation of the exercise machine 600, including actual T_(athlete),ω, and all settable and/or intrinsic loads that contribute to the loadexperienced by the rower 602. The numerical values used to set settableloads in the exercise machine 600 may be influenced by the measuredactivities of both the rower 602 and other rowers on other machines,real or simulated, hence the ability of various embodiments of thedisclosure to produce a joint training experience for rowers onphysically separate exercise machines. These general considerations,with other considerations discussed with reference to the illustrativeexercise machine 600 shown as a rowing machine, will be understood toapply also, with appropriate modifications, to other forms of exercisemachines and athletic apparatus. This disclosure now turns to portionsof the closed-loop control method employed by the illustrative exercisemachine 600.

As will be clear to persons familiar with electrical machines, theexcitation of an alternator, e.g., alternator 618, can be controlled bypulse-width modulation of the excitation current of the field winding,that is, by switching the field-winding voltage on and off at a fixedfrequency but with a variable duty cycle. The exercise machine 600 canthus adjust, by altering the duty cycle of a pulse-width-modulatedvoltage source, the average excitation current of the alternator 618,which in turn affects the torque load placed on the flywheel 616 by thealternator 618 and thus the load experienced by the rower 602. Toaccomplish this, the controller 632 calculates an estimate of a torquevalue, T_(athlete), that is applied by the rower 602 to the flywheel616. The calculation of T_(athlete) is based on several measuredvariables of machine operation along with a set of pre-recordedvariables representing physical characteristics of the exercise machine600. Calculations can be performed, in various embodiments, usingvarious algorithmic models. In one example, sensors monitor armaturevoltage V_(arm) of the alternator 618, a field current I_(fld) in thefield circuit of the alternator, and a rotational velocity ω of theflywheel 616. The rotational acceleration α of the flywheel 616 can beestimated from repeated measurements of the flywheel rotational velocityω. Additionally, an armature current I_(arm) of the alternator 618 canbe calculated based upon the sensed value of the armature voltageV_(arm). In an example, the power output of the alternator 618 can bebetween zero (0) and one (1) kilowatt.

The programmed physical characteristics of the exercise machine 600 caninclude resistance of the electrical load bank, R_(load) (which may in,various embodiments, be a controllable quantity); inductance of thefield circuit, L_(fld); resistance of the field R_(fld); resistance ofthe armature, R_(arm); inductance of the armature, L_(arm); mutualinductance between the armature and the field circuit 38, L_(af) momentof inertia of the flywheel 616, J; and a number of drivetrain dampingcoefficients, e.g., b₀, b₁, and b₂, so called because they appear intorque terms proportional to powers of ω. The values for L_(af), J,R_(arm), R_(fld), R_(load), b₀, b₁, and b₂ are system characteristicsinitially identified during design of the exercise machine 600 and canbe refined for each individual exercise machine 600 during a calibrationprocess at or near the end of the manufacturing process, or at a latertime.

In an example, the controller 632 can use the described values tocalculate an estimate of the applied torque value T_(athlete), which canbe a sum of a mechanical torque, T_(mech), and an electrical torque,T_(elec), using the following equations:

T _(athlete) =T _(mech) +T _(elec)  EQUATION 1

where T_(mech) is the sum of an inertial term and several drag terms,i.e.,

T _(mech)=(J×α)+b ₀+(b ₁×ω)+(b ₂×ω²)  EQUATION 2

and where

T _(elec) =L _(af) ×I _(fld) ×I _(arm)  EQUATION 3

Note that T_(elec) is proportional to I_(fld), where I_(fld) is areadily controllable quantity, as explained above. Also, I_(arm) may bevaried by changing the net resistance of the electrical load bank.

It is to be understood that EQUATIONS 1-3 are illustrative only, andthat additional or other variables and equations can be employed toestimate T_(athlete), and that other or additional variables can besensed to accomplishing the same purpose without departing from thespirit of this disclosure. For example, the current of the armature,I_(arm), can be sensed or measured and used directly in the aboveT_(elec) equation without sensing or measuring V_(arm) first and thencalculating I_(arm) using Ohm's law. Sensing or measuring any number ofvariables is anticipated by the present disclosure. Persons having skillin the art of electrical engineering will readily understand the abovecalculations, and also that it is possible to measure a variety ofvariables to use in various calculations to accomplish the same purpose.

The calculated value for T_(athlete) (e.g., rowing activity; torqueactually applied by the athlete) is applied to a dynamic model of adesired load profile (e.g., numerical model of a particular apparatus)to arrive at the appropriate load that the operator should experience. Adynamic model of the exercise machine 600 itself is then referenced forconverting the desired load to an appropriate actuation command For thepurposes of this disclosure, an appropriate actuation command can be anynumber of actions taken by the controller 632 to selectively modify theload experienced by the operator of the exercise machine 600.

In one example, the controller 632 can change at least one value used inone or both of the expressions for T_(mech) and T_(elec) shown above.Changing at least one of the values in these equations changes the loadexperienced by the operator. For example, the controller 632 can alterthe value of one or more of the values J, b₀, b₁, or b₂ of the T_(mech)equation so that the exercise machine 600 feels like an actualwatercraft; or, as noted above, I_(fld) and/or I_(arm) may be altered.By comparison, rowing devices according to the prior art can change thetorque load on the rower only if a damper is physically (usuallymanually) moved to increase or decrease an exposed area used for airpassage so that a flywheel loaded by a fan shifts its operating point ona continuum between acting as a predominantly inertial load (damper 100%closed) and acting predominantly as a pump (damper 100% open). Theclosed-loop methods of load control employed in various embodiments ofthe disclosure allow alteration of operator load at electronic speedsand thus, advantageously, the simulation of rapidly shifting, slowlyshifting, and constant real-world loads.

Moreover, the apparatus and methods of various embodiments enable thecontroller 632 to alter the torque load experienced by the operator tomatch a selected simulated-apparatus profile. In an example, thecalculated T_(mech) has to make up any difference between T_(elec) andthe desired torque load T_(athlete) based on the selected profile andstate of trainer operation. As shown in EQUATION 2, the value ofT_(mech) is a function of velocity and acceleration of the flywheel 616.One method of providing a different load for the exercise machineoperator (e.g., rower 602) is to change at least one of the dampingcoefficients for a given velocity of the flywheel 616 and then change atleast one of I_(fld) and I_(arm) to alter T_(elec) so that the actualvalue of T_(athlete) is equal to or is substantially equal to thedesired value of T_(load).

Moreover, the controller 632 can be programmed to replicate the loadfelt by an operator on any number of actual watercraft or exercisemachines. In one example, the described exercise machine 600 can mimicthe feel of known rowing machines. In other examples, the describedexercise machine 600 can mimic the feel of any number of actualwatercraft such as the previously mentioned one-person scull, two-personscull, four-person scull, two-person sweep, four-person sweep, oreight-person sweep. The exercise machine 600 can mimic any number ofother watercraft, exercise devices, etc. with each mimicked devicerepresented by a different profile that can be stored in the memory ofthe controller. Each profile can include changes to any number of the J,b₀, b₁, and b₂ values.

In one example, the process for mimicking a particular device can bedescribed as follows. The dynamic model is in the algorithm asrepresented in the T_(mech) equation shown above. This model can besimilar to some existing rowing machines that provide relatively closeapproximations of rowing while off the water. The controller 632 thenconducts calculations to match the load felt by the operator to what theoperator would feel as if they were rowing on the water in a particularwatercraft. The controller 632 then applies the resultant load (e.g.,T_(athlete)) to the dynamic model of the T_(mech) equation. Thecontroller 632 can include memory allocations for the inertia J anddamping coefficients b₀, b₁, and b₂ for the separately excited electricmachine 618.

For example, the flywheel 616 can be specified, designed, and/orconstructed to have particular inertia value J. In some examples, theb₀, b₁, and b₂ damping coefficients are almost negligible. Additionally,in some examples, there can be additional damping coefficients; however,these terms are often not significant enough to substantially affect thecalculation result. The controller 632 will then calculate a value forT_(athlete) (the load felt by the operator) using the constants forL_(af), J, b₀, b₁, and b₂.

The controller 632 then accesses a desired torque value for theparticular desired profile (e.g., a four-person scull) selected by theoperator. Because T_(elec) is controlled, the controller 632 willconduct calculations to augment the T_(elec) value with a new T_(mech)value such that the T_(athlete) is equal to or is substantially close tothe desired torque value for the desired profile. In one example, thesame T_(mech) and T_(elec) equations are used by the controller 632,except that new values for the inertia and damping coefficients replacethe previous ones, for example the equation can use J′, b₀′, b₁′, b₂′rather than J, b₀, b₁, and b₂ to calculate a value for T_(mech). Thecontroller 632 will then add the T_(elec) and the new T_(mech) torquevalues to ascertain whether actual T_(athlete) is equal to or issubstantially close to the desired T_(athlete). If not, the controller632 can re-calculate T_(mech) using yet another set of inertia anddamping coefficients. This process can continue within the controlleruntil an appropriate T_(athlete) value is attained.

The controller 632 then applies the known inertia and dampingcoefficients to the T_(mech) equation to make the exercise machine 600“feel like” the selected apparatus (e.g., a four-person scull). Eachactual apparatus moves very differently on the water; e.g., it is to beappreciated that a one-person apparatus can exhibit relatively fastacceleration values and have a relatively low top speed on the water.Another apparatus, such as an eight-person apparatus, can exhibitrelatively slow acceleration and have a relatively high top speed. TheT_(mech) equation shown above can mimic each of the apparatus and theirvarious characteristics with the proper values for J, b₀, b₁, and b₂.

It is to be appreciated from the above equations that the torque loadthe operator experiences (T_(athlete)) is a function of the current atthe armature (I_(arm)), which can be calculated after measuring orsensing V_(arm), and of the current through the field circuit (I_(fld)),which is a closed loop control variable. The controller 632 constantlymeasures and adjusts the I_(fld) modulator to produce the desiredT_(athlete). In one example, if I_(fld) is higher than the valuerequired to replicate the selected profile, the controller 632 candecrease the duty cycle of I_(fld) to reduce the average (effective)I_(fld). Similarly, the controller 632 can increase the duty cycle ifthe value of I_(fld) is too low. The controller 632 can monitor andadjust I_(fld) at relatively short intervals such that I_(fld) isadjusted as needed. In this way, I_(fld) is controlled such that theexercise machine 600 can approximate real-world conditions of variousrowing apparatus as described above.

Referring again to FIG. 6B, in one example, wherein the exercise machineis in at least some modes of operation self-powering, the battery 638can provide the controller 632 with electrical power. Additionally, thebattery 638 can provide power to the field circuit of the alternator 618for a relatively short time as the rower 602 begins to operate theexercise machine. Once the operator 602 begins moving the connectivestructure 610 (e.g., by rowing), the electrical converter 636 willreplenish electrical charge removed from the battery 638 while theoperator 602 completes one or more strokes during an exercise period. Inan example, electrical energy can be diverted from the electricalcircuit of the electric machine 618 before the electrical signal reachesthe electrical load bank 626, and the diverted electrical energy can besupplied to the battery 638. In another example, the battery 638 candraw power from the electrical load bank 626 to maintain a charge. As analternative, a standard wall power supply (e.g., 110-volt supply, notdepicted) can be used to provide power to the battery 638. In yetanother example, a battery charger can accept electrical supply from acombination of the standard wall power supply and the electrical energycreated by operating the exercise machine 600.

The exercise machine 600 can communicate with at least one additionalassociated exercise machine (e.g., via the direct-interconnect topologyof FIG. 4A, the centralized topology of FIG. 5, or some other topology).Communication between exercise machines can provide the benefit ofhaving multiple operators working out on multiple machines against aneffectively shared load. For example, an operator in one location canoperate an exercise machine set to a desired load profile to replicate afour-person scull, while three additional operators can operate threeadditional exercise machines with the same desired load profile, eachoperator working against the same load. In an example, the exercisemachine 600 exchanges activity data with each of the three associatedexercise machines, and this data can be incorporated in controllerand/or server calculations to achieve desired closed-loop controlcharacteristics.

Various suitable algorithms can incorporate various data items,including activity data from multiple machines, to achieve desiredclosed-loop control characteristics with the apparatus and methods ofthe present disclosure. In an example where machine 600 is one of Pcomparable exercise machines (e.g., with similar flywheels) combinedvirtually in a group-training fashion, using the inertia J of theflywheel 616 and the desired acceleration α_(des) of the flywheel 616,one can calculate a net torque, T_(net), acting on the flywheel 616using

T _(net) =J×α _(des)

Solving for desired rotational acceleration α_(des), one obtains:

α_(des) T _(net) /J

If the desired rotational velocity of the flywheels of the P machines isω_(des), then, integrating with respect to time,

ω_(des)∫α_(des)

This can be combined with all known applied torque(s) from each of theassociated exercise machines to determine a desired rotational velocity,ω_(des), for the flywheels using desired damping coefficients b_(0des),b_(1des), and b_(2des):

∫_(des)=∫((T _(crew) −{b _(0des)+(b _(1des)×ω)+(b _(2des)×ω²)})/J_(des))  EQUATION 4

In EQUATION 4, J_(des) is the desired flywheel inertia, to is the actualrotational velocity of the flywheel, and

T _(crew) =ΣT _(athlete)(i)/P, i=1, . . . P

where T_(athlete)(i) is the torque applied by the ith of the P athletes.

T_(net) in the above description is the desired T_(load), and, theT_(crew) term can be calculated for an arbitrary number of athletes asappropriate.

EQUATION 4 can be used to directly perform closed loop speed control.Any number of closed loop control methodologies can be applied toachieve desired closed loop control characteristics. Examples ofclosed-loop control methodologies can include, but are not limited to:proportional-integral-derivative control, lag-compensation, h-infinity,state-space, etc.

Many activities are enabled by the foregoing and various otherembodiments of the disclosure that were not enabled at all, or wereenabled less conveniently or more expensively, by the prior art. Anon-exhaustive list of illustrative use cases is hereby presented toillustrate the highly flexible potential of embodiments of thedisclosure:

-   -   An athlete may exercise on an isolated exercise machine at a        fixed load level without engaging a load profile (virtual        apparatus): that is, the athlete may engage in normal        stand-alone machine exercise, as on a typical prior-art machine.    -   An athlete may exercise on an isolated exercise machine which        simulates the load profile of a specific athletic apparatus.    -   An athlete may exercise on a networked exercise machine as part        of a virtual team of other real athletes on other exercise        machines jointly operating a specific virtual apparatus, where        the athletes involved may be at various geographical distances        from each other.    -   An athlete may exercise as part of a virtual team of whose other        members one or more are simulated.    -   Athletes may be combined and recombined by manipulation of        appropriate software into various teams of various sizes        operating various virtual apparatuses, and/or moved between        virtual positions in a given virtual apparatus.    -   A virtual team of real athletes may compete against one or more        virtual teams, whose members may be partly or entirely real or        partly or entirely simulated.

Having described the foregoing embodiments of the disclosure, it will beapparent to those of ordinary skill in the art that other embodimentsincorporating the concepts disclosed herein may be used withoutdeparting from the spirit and scope of the disclosure. The describedembodiments are to be considered in all respects as only illustrativeand not restrictive.

1. A rowing exercise machine, comprising: a mechanical energy storagedevice; a handle coupled to the mechanical energy storage device via aconnective structure wherein relative movement of the handle withrespect to the mechanical energy storage device urges motion of themechanical energy storage device; an apparatus configured to dynamicallysupplement a resistance of the mechanical energy storage device with anadded resistance; and a controller in communication with the mechanicalenergy storage device and the apparatus, the controller having computerreadable instructions to determine the added resistance and todynamically and selectively adjust the added resistance to alter a loadexperienced by a rower participating in a group exercise by applyingforce to the handle; and a communication pathway between the controllerof the rowing exercise machine and a controller of at least oneadditional associated rowing exercise machine that permits applicationof the forces applied in each of the rowing machines to a shared load ofa multi-rower watercraft.
 2. The rowing exercise machine of claim 1,wherein the shared load of a multi-rower watercraft is one of a twoperson scull or a four person scull.
 3. The rowing exercise machine ofclaim 1, wherein the shared load of a multi-rower watercraft is one of atwo person sweep, a four person sweep, or an eight person sweep.
 4. Therowing exercise machine of claim 1, wherein the apparatus comprises anelectrical load bank.
 5. The rowing exercise machine of claim 1, whereinthe communication pathway comprises a network topology.
 6. The rowingexercise machine of claim 1, further comprising an apparatus configuredto provide visual indication of an action taking place on the at leastone additional associated exercise machine.
 7. The rowing exercisemachine of claim 1, further comprising a user interactive apparatusconfigured to provide aural indication of an action taking place on theat least one additional associated exercise machine.
 8. The rowingexercise machine of claim 1, wherein the rower is participating in agroup exercise performed in a simulated multi-rower watercraft against aworkload shared with at least one other rower.
 9. The rowing exercisemachine of claim 1, wherein the at least one rower is a real roweroperating another rowing machine as part of the group exercise.
 10. Therowing exercise machine of claim 1, wherein the handle is configured toreplicate a handle of an oar used when the multi-rower watercraft is oneof a two person scull or a four person scull.
 11. The rowing exercisemachine of claim 1, wherein the handle is configured to replicate ahandle of an oar used when the multi-rower watercraft that is one of atwo person sweep, a four person sweep, or an eight person sweep.
 12. Therowing exercise machine of claim 1, comprising an electrical generator.13. The rowing exercise machine of claim 12, wherein the electricalgenerator is an electric machine and wherein the controller furthercomprises computer readable instructions for adapting a responsivenessof the electric machine based on a watercraft apparatus selected for thegroup exercise.
 14. The rowing exercise machine of claim 1, wherein themechanical energy storage device is a flywheel.
 15. The rowing exercisemachine of claim 1, wherein the controller selectively modifies the loadexperienced by the rower to simulate rapidly shifting, slowly shifting,and constant real world loads of the multi-rower watercraft asinfluenced by an individual effort of each of the rowers in themulti-rower watercraft.
 16. The rowing exercise machine of claim 15,wherein the controller adjusts and then applies one or more drive traindamping coefficients to the load experienced by the rower in response toa sum of an individual effort of the each of the rowers in themulti-rower watercraft.
 17. A kit for modifying an existing rowingmachine, comprising: an electric machine; a mechanical energy storagedevice; a transmission for coupling the electric machine to themechanical energy storage device; an electrical load bank to be coupledto the electric machine; a controller to be placed in communication withthe electric machine and the electric load bank and having computerreadable instructions to selectively adapt an operation of the electricmachine or the electric load bank to provide a dynamic selectivealteration of a load experienced by a user of the rowing machine; and anelectronic memory in communication with the controller, the electronicmemory containing computer readable instructions having loadcharacteristics of multi-rower watercraft providing a shared load to oneor more associated rowing machines, wherein the kit components are usedto modify an associated existing exercise machine thereby enabling fieldupgrade of said associated existing exercise machine to be capable ofcommunication with at least one additional associated exercise machine,wherein a total resistance in said associated exercise machine isduplicated in an additional associated exercise machine such that afirst rower operating said exercise machine and a second rower operatingsaid additional associated exercise machine operate as a virtual team.